The present invention relates to a location system for establishing the position of a portable or mobile terminal and in particular to a location system employing location beacons.
In telecommunication systems of the type having one or more mobile or portable terminals, for example a portable mobile radio telephone handset, the ability to determine the location of such a terminal can be of benefit with respect to the operation and the functionality of the system. Information relating to the location of the mobile terminal allows operational parameters to be adjusted for optimising performance and the use of resources. Furthermore, the ability to establish the actual position of a mobile or portable terminal is useful in its own right, since by equipping a user with such a terminal it is possible to locate the user and track their movements. This is of particular benefit where the user is a lone worker, someone operating in hazardous environments, or perhaps a member of the medical profession or a member of a maintenance team. The ability to locate and track security personnel is of particular benefit.
The accuracy to which the position of a portable terminal (and hence the user of the terminal) needs to be established will vary depending on the reason for gathering the location information and the environment. In the case of a farm worker in an empty field, for example, it may be sufficient to merely establish that the worker is in the field. Accurate location of the worker is not required and the worker may be located visually. In contrast, a security guard whose welfare is a prime consideration needs to be located with a greater accuracy, especially if working within a building having a number of rooms or corridors that will render visual contact impossible. It will be apparent that a location system should be capable of providing location information of a portable or mobile terminal to the required accuracy.
In a wireless telecommunications system having one or more base station for communication with the portable terminals, the only information normally available that relates to the location of a terminal is obtained through knowing which base station is handling the communication with the portable terminal and also knowing where the base station is located.
One known communication system provided with means for detecting the position of portable terminals is the subject of the abstract of Japanese patent application number JP 0 7 274240A. The system includes a number of beacon oscillators geographically distributed around the operating domain of the portable terminals. The beacon oscillators emit a position signal that is picked up by a nearby portable terminal via a RF receiver provided in the portable terminal. Any such position signal, if picked up by the portable terminal, is combined with an identification signal of that associated with that portable terminal and relayed by the mobile terminal to a host computer of the communication system. The combined signal is sent to the computer via a radio transceiver provided in the portable terminal which transceiver communicates with a radio master station that is connected to the host computer.
A problem with this system is that the portable terminal uses an RF section for communicating with the radio master station and a further RF section for receiving information from the beacons. The presence of two RF sections as opposed to one is likely to increase cost and complexity of the portable terminal. Furthermore, should it be desirable to provide a known, established, communications system such as a GSM mobile radio cellular telephone system or the like with a location system operating in accordance with the principles of the cited known art, each portable terminal must be replaced by one having the additional hardware for receiving signals from the beacons. If beacons were merely added to the established system, existing portable terminals would not be able to detect their presence.
Another potential problem is the additional power consumption that a separate, additional RF section can give rise to. Furthermore, some type of power management would be highly desirable because an additional RF section that is continuously operating to receive beacon signals will place a significant demand on power requirements. This is undesirable where the power supply is exhaustible, for example as is the case when the power is provided by a battery.
In this type of known system where beacons transmit to portable terminals, failure of a location beacon results in the position signals from that beacon ceasing. Unfortunately such a condition is not readily apparent to the system since the portable terminals cannot differentiate between this condition and the condition of merely being out of range of that beacon. Therefore, in this type of system, it is necessary to routinely visit and locally test each beacon which can be time consuming. Furthermore, such testing may also be difficult if the beacon is not easily accessiblexe2x80x94for example in those cases where it is out of reach, buried in a wall or located in some other dangerous environment.
It is an object of the present invention to provide a location system that will allow the position of a portable terminal to be established with a greater accuracy than is provided through merely knowing which base station is handling the communication with the portable terminal and also knowing where that base station is located.
It is yet another object of the present invention to provide a location system that will allow the position of a portable terminal to be established, wherein any additional power consumption of the portable terminal as a result of being provided with the location system is minimal in comparison to a portable terminal not benefiting from the system of the present invention.
In accordance with the present invention there is provided a location system for establishing the position of a portable terminal that transmits identity information indicative of the identity of the individual terminal at a first predetermined power level, the system including: one or more such portable terminal; at least one location beacon having a known position and capable of receiving identity information, and a control unit, wherein the location beacon is provided with means for generating an output signal when identity information is received at the beacon with a power level greater than a predetermined threshold value, the output signal indicating that a portable terminal is within a particular distance range from the beacon, and means for making the output signal available to the control unit.
The identity information transmitted by the portable terminal may be transmitted continuously, intermittently or on demand. In the latter case this may be initiated by a component of the system. Alternatively it may be initiated by the user of the portable terminal, for example by issuing a command to initiate a communication or through originating a call, such as an alarm call.
It is noted that information (in the form of the beacon output signal) is made available to the control unit from the location beacons, in contrast to the above mentioned known system where information is sent to the host computer from the portable terminal. The difference in this chain of communication has an inherent advantage since it can permit the control unit to identify defective or failed location beacons, as those beacons will never produce an output signal. Indeed, the beacons could make available a signal to the central control unit periodically to indicate correct operation.
Communication between the central control unit and the location beacons may be enhanced to provide two way communication. Such communication can allow remote monitoring of the beacons to establish correct functionality and allow changes to be made to beacon operating parameters remotely. Where the beacons include a software component, system or application software could be downloaded to the beacons remotely. All of these features are especially useful if the beacons are not readily accessible.
Where the portable terminal is also provided with other communication functions, for example as a mobile or cordless telephone is for communication of voice or data files, the identity information may be transmitted with the same power that is used for transmission of information associated with the other communication functions, or the identity information may be transmitted with a different power. This can be used to add flexibility to the system in terms of reducing power consumption. Because the portable terminal transmits rather than receives identity information this eliminates the need for the portable terminal to monitor for location beacon signals (an activity which has potential for significant power consumption). This can allow additional control over power consumption due to the activity of transmitting identity information. For example, the identity information could be transmitted less often to conserve power.
The portable terminals may be mobile components, such as handsets of a mobile or cordless telephone system, pagers or mobile computing apparatus. Indeed portable terminals may include portable communications devices that are configured to perform a particular function or may be configured to perform one of a number of functions.
A plurality of location beacons may be provided. The system may then include means for distinguishing between outputs of different location beacons. It is preferable that each location beacon generates an output signal that may be distinguished from outputs produced by other location beacons.
One, several, or all beacons may be provided with means for setting the predetermined threshold value. Furthermore, one, several of all beacons may be provided with means for adjusting the predetermined threshold value. If more than one beacon is present within the system the threshold value of individual beacons may be set and/or adjusted independently of the threshold values of other beacons. This has the advantage of allowing beacons to be individually tailored to detect portable terminals within particular chosen distance ranges.
Where two way communication between a beacon and the control unit is provided, it may be possible to alter the threshold value of that beacon remotely from the control unit.
Preferably the control unit holds information relating to the positioning of the or each location beacon therefore allowing an output signal of a given beacon to be associated with that position. If information relating to the threshold value of the beacons is also known this will give an indication of the coverage area of a particular beacon and therefore the accuracy to which the position of a portable terminal may be established, based on the occurrence of a particular beacon output signal.
Whilst the location system of the present invention may be implemented separately, in a preferred embodiment it is integrated in a telecommunications system.
In one arrangement the portable terminal is based on a DECT portable part and the terminal exchanges information in a manner based on the DECT standard. (DECT is an abbreviation for Digital Enhanced Cordless Telecommunications and is defined in standard ETS 300 175 of the European Telecommunications Standards Institute. The Standard includes a number of parts.) Furthermore the location beacons may be based on a DECT portable part and the beacons exchange information in a manner based on the DECT standard. In each case some deviation from the standards may be necessary to obtain the required operation.
Other aspects and optional features of the present invention appear in the appended claims, to which reference should now be made and the disclosure of which is incorporated herein by reference.